1. Field of the Invention
The present invention generally relates to the diagnosis of abnormal conditions in the lungs by the use of a diagnostic catheter, such as the sampling of a patient's lungs by using a bronchoalveolar lavage catheter. More particularly, the present invention relates to a method and apparatus for securing the longitudinal position of a diagnostic catheter while the diagnostic catheter is advanced into the lungs of a patient, while preventing the interruption of prescribed ventilating parameters.
2. Background Art
Various types of medical procedures involve the insertion of a tubular device within the human body. The types of tubular devices used are diverse, allowing for the insertion of various types of tubular devices for both treatment and diagnosis of a patient's body. One of the most common areas subject to the insertion of a tubular device include the upper respiratory tract. This area of a patient's body can be subject to bronchial washing, brush biopsy, needle biopsy, and in particular, bronchoalveolar lavage with or without bronchoscopy. The technique of bronchoalveolar lavage has become common in the diagnosis of infections and other abnormalities in the alveoli at the terminus of the bronchiole in the lungs of a patient. In bronchoalveolar lavage, occasionally referred to as "BAL", a sterile fluid is infused in aliquots of about 30 ml. each through the upper respiratory system of a patient into the portion of the lungs thereof designated for study. The fluid infused is then aspirated and cultured and examined in order to isolate and identify infections, fungi, cells, and other signs of inflammation thusly flushed from the walls of the alveoli.
A helpful background statement on the nature and useful findings related to the use of bronchoalveolar lavage is the American Thoracic Society, "Clinical Role of Bronchoalveolar Lavage in Adults with Pulmonary Disease", 142 AMERICAN REVIEW OF RESPIRATORY DISEASE, 481-486 (1990), which is incorporated herein by reference.
Very often, when bronchoalveolar lavage is conducted, a patient is being mechanically ventilated. This requires that the patient's respiratory tract be coupled to a respirator which can provide continuous airflow within established ventilating parameters. Conducting bronchoalveolar lavage under these circumstances may require the interruption of this ventilation, or at least the disruption of the established ventilating parameters. The respiratory hoses are lavage catheter is inserted into the tracheal tube of the patient.
The interval between the interruption of the ventilated gases to the patient may be short and temporary, but any interruption results in the oxygen level of the blood decreasing, and in the heart and lungs working harder. These metabolic changes can be dangerous to a critically ill patient. Also, the physical manipulation of many tubes, which often times requires more than one medical personnel to coordinate, can extend the time of the interruption, and therefore increase the dangers to a critically ill patient.
The critical need for ventilated air is clarified by examining how ventilated air operates relative to a patient. Mechanical ventilation generally, but not exclusively, involves ventilating air under positive end expiratory pressure (PEEP). PEEP maintains a large number of a patient's lung alveoli open during the respiratory support, thereby increasing the effective lung area of ventilation and decreasing ventilation defects. In some patients the interruption of PEEP leads as an immediate effect in a sudden collapse of lung alveoli.
Besides the interruptions in the ventilating circuit inherent, when the bronchoalveolar lavage catheter is advanced within a tracheal tube, there are further drawbacks with current bronchoalveolar lavage practices. First, there are no means provided for securing the longitudinal position of a diagnostic tube inserted into a ventilating circuit, relative to a patient. Successful diagnostic examinations of the lower respiratory tract of a patient depends on the stable placement of a diagnostic tube. In bronchoalveolar lavage, the distal tip of a catheter is wedged into a position in a bronchiole in a lung of a patient. Were the catheter to move longitudinally during the diagnostic sampling it could become unwedged, aspiration might cease to be effective, and the specimens collected could yield specimens which are inadequate leading to inaccurate data.
Recent literature has forecast a rise in the frequency with which medical practitioners can be expected to resort to the use of bronchoalveolar lavage. The increased incidence of acquired immune deficiency syndrome (AIDS) and other therapeutic-related immunocompromising treatments, such as chemotherapy, gives rise to a large number of patients susceptible to multiple and exotic lung infections. Therefore, medical practitioners can be expected to resort to the use of bronchoalveolar lavage on a greater number of infected patients.
Exhaled air from an individual infected with AIDS is directed outwardly through a tracheal tube. Normally, the exhaled air travels through a sealed circuit from the tracheal tube through a hose to a mechanical respirator. In this instance, the contaminated exhaled air is isolated from surrounding medical personnel.
The circuit is unsealed, however, when the hose is disconnected from the tracheal tube to advance a diagnostic catheter into the respiratory tract of the infected AIDS patients. The exhaled air may also contaminate the environment surrounding a non-mechanically ventilated patient. Although, deflected in some instances, the exhaled air communicates from the tracheal tube to the surrounding environment. In these instances, possibly contaminated air traveling unconfined from an infected patient could travel in a path towards medical personnel and be a threat to those performing bronchoalveolar lavage. Reducing medical personnel's possibly infectious contacts with airborne contaminants, therefore, is a prudent step.